This invention relates to a radiation image processing method and a radiation image processing apparatus.
Heretofore, an apparatus for reading a radiation image capable of obtaining a radiation image for diagnosis of disease has been known. In this radiation image reading apparatus, it is used, for example, a stimulable phosphor sheet wherein stimulable phosphor material, which stores a part of radiation energy and later, when an exiting light such as a visible light is applied, exhibits stimulated emission of light in accordance with the stored energy, is processed to make a sheet. In an apparatus using this stimulable phosphor sheet, radiation image information of an object to be radiographed is recorded by applying a radiation transmitted through the object to the stimulable phosphor sheet, and by condensing and converting it into an electrical signal by a photoelectric element the stimulated emission of light obtained by application of a laser light or the like to the stimulable phosphor sheet in which the information has been recorded, image data of a radiation image based on this electrical signal are generated. Further, it is also used an apparatus wherein image data are generated on the basis of an electrical signal which is generated in accordance with the dose of the applied radiation by two-dimensionally arranged plural detective elements which is called a Flat Panel Detector (an FPD).
However, in the FPD, wherein a plurality of detective elements are arranged two-dimensionally, the signal level (signal value) for the dose of applied radiation is not uniform for all the detective elements, and in some cases it is included a detective element such as a damaged element or an inferior element which makes the signal level different from the level of other elements, that is, an abnormal level, (hereinafter referred to as xe2x80x98a defective pixelxe2x80x99). In cases where such a defective pixel is included, because an image defect is produced in the image data based on the signal read from the image sensing panel, sometimes proper diagnosis is disturbed in reading the photographed image for diagnosing a disease.
Therefore, the first object of this invention is to provide a radiation image processing method and a radiation image processing apparatus wherein a satisfactory radiation image can be obtained even if an image defect is produced in the image data.
Further, if correction has been done when an image defect was produced, the position for which the correction has been made can not be discriminated from the image data after correction; hence, it is impossible to confirm the position for which correction has been done.
Therefore, it is another object of this invention to provide a radiation image processing apparatus capable of obtaining a radiation image which is satisfactory and easy to observe even in the case where an image defect has been produced, and also capable of easily discriminating the position of the image defect.
Further, image defects sometimes increase; hence, correction can not be precisely done if the increase of image defects and the positions of the image defects are not grasped precisely.
Accordingly, it is a further object of this invention to provide a radiation image processing apparatus capable of correctly detecting that an image defect has been produced newly and easily discriminating the image defect.
The above objects can be attained by the following structure and the following method.
A radiation image processing apparatus, comprises:
a defect detecting device to receive first image data from a sensor which comprises plural elements arranged two-dimensionally, converts irradiated radiation into electoric image signals by the plural elements and outputs image data in which each element outputs an image datum of a single pixel, the defect detecting device to detect an image defect in the first image data and to produce defect information indicating a position of the image defect;
a memory to store the defect information; and
a correcting device for receiving second image data outputted from the sensor on a condition that the sensor is irradiated with radiation passing through an object, for correcting the second image data on the basis of the defect information read out from the memory, and for producing third image data.
A radiation image processing apparatus, comprises:
a sensor in which plural elements are arranged two-dimensionally, to convert irradiated radiation into electoric image signals by the plural elements and to output image data in which each element outputs an image datum of a single pixel;
a defect detecting device to receive first image data from the sensor, to detect an image defect in the first image data, and to produce defect information indicating a position of the image defect;
a memory to store the defect information;
a defect comparing device to compare predetermined first defect information with second defect information based on new defect information newly produced by the defect detecting device; and
a warning device to make warning.
A radiation image processing apparatus, comprises:
a sensor in which plural elements are arranged two-dimensionally, to convert irradiated radiation into electoric image signals by the plural elements and to output image data in which each element outputs an image datum of a single pixel;
a defect detecting device to receive first image data from the sensor, to detect an image defect in the first image data, and to produce defect information indicating a position of the image defect;
a memory to store the defect information;
a defect comparing device to compare predetermined first defect information with second defect information based on new defect information newly produced by the defect detecting device; and
the memory renewing the stored defect information based on the comparison result by the defect comparing device.
A radiation image processing method, comprises steps of:
producing first image data by a sensor which comprises plural elements arranged two-dimensionally, converts irradiated radiation into electoric image signals by the plural elements and outputs image data in which each element outputs an image datum of a single pixel;
producing defect information indicating a position of the image defect by detecting an image defect in the first image data;
producing second image data by the sensor on a condition that the sensor is irradiated with radiation passing through an object, and
producing third image data by correcting the second image data on the basis of the defect information.
Further, the above objects can be attained by the following preferable structure and the following preferable method.
The radiation image processing method of this invention is a method wherein an output signal is obtained from two-dimensionally arranged plural radiation detecting elements with each of the radiation detecting elements made as one pixel, and an image defect is detected from first image data produced on the basis of the output signal, while a defect information showing the position of the detected image defect is generated, and the image data of the image defect shown by the defect information in second image data generated by applying the radiation transmitted through an object to be radiographed to the plural radiation detecting elements are corrected.
Further, the radiation image processing apparatus is an apparatus comprising defect detecting means which detects an image defect from first image data produced on the basis of an output signal obtained from two-dimensionally arranged plural radiation detecting elements with each of the radiation detecting elements made one pixel and generates the defect information showing the position of the detected image defect, defect information memorizing means which memorizes the defect information generated by the defect detecting means, and defect correcting means which corrects the image defect in second image data produced by applying the radiation transmitted through an object to be radiographed to the plural radiation detecting elements on the basis of defect information memorized in the defect information memorizing means.
In this invention, at least one out of image data produced without application of radiation, image data produced by applying radiation uniformly, and image data produced by applying the radiation transmitted through an object to be radiographed is taken for the first image data. Further, image data subjected to trend removal is taken for the first image data.
Now, the defect information showing the pixel position of the detected image defect is generated through carrying out any one detecting process or plural detecting processes out of the following: a detecting process wherein a first threshold value and a second threshold value which is higher than the first is determined, and if signal level of a pixel in the first image data is lower than the first threshold value or higher than the second threshold value, this pixel is judged as an image defect, a detecting process wherein a pixel in the first image data is judged as an image defect if signal level of the pixel is different from the average signal level of the surrounding pixels by an amount not less than a predetermined value, a detecting process wherein average signal level of image data across a predetermined number of lines taken in the longitudinal or lateral direction is used as the first image data, and if the average level is lower than the first threshold value or higher than the second threshold value, the pixels across the predetermined number of lines are judged as image defects, and detecting process wherein average signal level of image data across a predetermined number of lines taken in the longitudinal or lateral direction is used as the first image data, and if the average level is different from the average level of the surrounding pixels by an amount not less than a predetermined value, the pixels across the predetermined number of lines are judged as image defects. For the second image data produced by applying the radiation transmitted through an object to be radiographed to the plural radiation detecting elements, the correction of an image defect is performed in a manner such that the image data of the image defect is substituted, for example, by the average level of the image data of the normal pixels surrounding the defective pixel.
A radiation image processing apparatus of this invention comprises image data generating means for generating image data on the basis of an output signal from a plurality of radiation detective elements which are arranged two-dimensionally, image defect detecting means for detecting an image defect by using first image data generated by said image data generating means and generating defect information indicating the position of the detected image defect, defect information memorizing means for memorizing the defect information generated by said image defect detecting means, and image defect correcting means for correcting the image defect of second image data generated by applying the radiation having been transmitted through a photographic object to said plurality of radiation detective elements and generating third image data, said radiation image processing apparatus further comprising image data processing means for processing said second image data and said third image data as a unit of image data.
Further, the radiation image processing apparatus further comprises image display means and image data supplying means for supplying image data to said image display means, wherein said image data supplying means supplies either the second image data or the third image data alternately by switching to said image display means, or supplies both of them to said image display means, and a radiation image based on the image data supplied from said image data supplying means is displayed on said image display means.
Furthermore, said radiation image processing apparatus further comprises image data outputting means, wherein both the second image data and the third image data are processed in such a manner as to become capable of being outputted to a sheet of medium and outputted to it.
In this invention, the image data before correction for image defects and the image data after correction for the defects are processed as a pair of data, and a radiation image before correction and the radiation image after correction are simultaneously or alternately displayed on the basis of these image data having been made to be a pair. Further, the image data having been made to be a pair are outputted together. Further, by using information indicating the positions of image defects instead of the image data before correction or the image data after correction, a display indicating the positions of image defects or the information indicating the positions of image defects is carried out. In this case, for example, in the case where the number of pixels of the display means for displaying the radiation image is smaller than the number of pixels of the image data to be displayed, the image data are thinned in such a manner as to have a minimum number of image defects. Further, in an external apparatus in which the image data are outputted to a sheet of medium as a radiation image, in the case where the number of pixels to be able to be outputted to a sheet of medium is smaller than the number of pixels of the image data, the image data which are thinned in such a manner as to have a minimum number of image defects in accordance with this external apparatus are outputted from the radiation image processing apparatus to the external apparatus.
A radiation image processing apparatus of this invention comprises image data generating means for generating image data on the basis of an output signal from a plurality of radiation detective elements which are arranged two-dimensionally, defect detecting means for detecting an image defect by using first image data generated by said image data generating means and generating defect information indicating the position of the detected image defect, defect information memorizing means for memorizing the defect information generated by said defect detecting means, defect comparing means for comparing a predetermined first defect comparing information with a second defect comparing information of image defects based on the defect information which is newly generated in said defect detecting means, and notifying means for issuing a warning on the basis of the result of comparison in said defect comparing means. The radiation image processing apparatus further comprises display means; the positions of image defects based on the defect information generated newly in the defect detecting means are displayed on the display means, and when it has been judged that the defect positions of the second defect comparing information include new defect positions which are different from the defect positions of the image defects based on the defect information memorized in said defect information memorizing means, also the new defect positions which are different from the defect positions of the first defect comparing information are displayed by marking.
Further, the radiation image processing apparatus comprises image data generating means for generating image data on the basis of an output signal from a plurality of radiation detective elements which are arranged two-dimensionally, defect detecting means for detecting an image defect by using first image data generated by said image data generating means and generating defect information indicating the position of the detected image defect, defect information memorizing means for memorizing the defect information generated by said defect detecting means, defect comparing means for comparing a predetermined first defect comparing information with a second defect comparing information of image defects based on the defect information which is newly generated in said defect detecting means, and in said defect information memorizing means, the defect information memorized is renewed on the basis of the result of comparison by said defect comparing means.
In this invention, in photographing a radiation image, for example, a maximum allowable number of image defects is set as the first defect comparing information, and this first defect comparing information is compared with the number of defects of the second defect comparing information of the image defects based on the defect information which has been newly generated by the defect detecting means. In this case, in the case where the number of defects of the second defect comparing information is larger than the number of defects of the first defect comparing information, a warning that the number of defects has exceeded the maximum allowable number of defects is issued by the notifying means by a voice etc. Further, when the number of image defects based on the information memorized in the defect information memorizing means is set as the first defect comparing information, and the number of image defects of the second defect comparing information has exceeded the number of defects of the first defect comparing information, or when it exceeds the number of image defects of the first defect comparing information by more than a predetermined value, a warning notifying the above is issued and the defect information which has been newly generated by the defect detecting means is substituted for the defect information memorized in the defect information memorizing means, or is added to it.
Further, when the positions of image defects based on the defect information memorized in the defect information memorizing means are set as the first defect comparing information, and it has been judged that the defect positions of the second defect comparing information include a new defect position which is different from any one of the defect positions of the first defect comparing information, a warning notifying the above is issued and the defect information which has been newly generated by the defect detecting means is substituted for the defect information memorized in the defect information memorizing means, or is added to it.
Furthermore, on the basis of the renewed defect information in the defect information memorizing means, correction of the image data is done by defect correcting means.